I have a quick question about a concept in android. Lets say I created my app that has bunch of buttons.

Now lets say, I decide to add a an animated circle (sort of like starting from a dot and drawing itself to become a a circle).

Do I achieve this by adding a Custom View on top of it and do the drawing on the OnDrawMethod?
Or is there a mechanism where I call draw around certain pixels on the screen?
Or some other way of achieving this?

Basically I want to know how to draw things on top of existing things.